The invention relates to a transmission control activated by auxiliary power.
In trucks above a certain size, it is necessary to shift into the individual gears via remote control, i.e., with the operator controlled gearshift mechanism connected to the transmission by an auxiliary power unit. Compressed air is normally used as the auxiliary power. This carries various advantages along with it. While the force for shifting into the gears, which large transmissions require, is quite high, it is not necessary with a transmission activated by auxiliary power to locate the transmission directly below the gearshift lever.
In addition, there are other advantages, such as a constant activation force and the capability of installing the activation cylinders at suitable points in the transmission.
The gearshift control mechanism in motor vehicles is generally executed in an H-shaped arrangement. For large trucks, a transmission with 12 speeds is especially suitable. These speeds can, for example, be achieved by a main transmission having the gearshift control arranged in a double H configuration. The auxiliary gearshift may be provided to double the number of normal gears.
To shift the gears with a transmission with a double H gearshift control arrangement, two activation cylinders are necessary, namely, a transfer mode cylinder and a drive mode cylinder. The transfer mode cylinder is used to set the drive track with four positions for the speeds R (Reverse) 1/2, 3/4, 5/6.
The drive mode cylinder is used to set the speeds, with three positions for forward, reverse and neutral.
With auxiliary-power activated shifting of the gears, different actuating forces are required, according to the gear selected. This is a function of the speed necessary for synchronization which, for example, is the highest for the first speed. After the shifting of the gear has been accomplished, the force should cease, to protect the mechanism.